I have no experience with the 300wsm but know from what I have read it should be an excellent choice. I do own 2 Tikka's and they have been very accurate and dependable rifles. The trigger on them is the best I have used on a factory setup and is easily adjusted yourself down to about 2 pounds and breaks super clean with no creep at all.
Do you already have the rifle or is it one you are just considering? I believe the Tikka uses one action length foa all chamberings so you are not really getting a shorter action or saving any weight and another caliber choice could be possible for the same weight. That said mine is a 270wsm that I just had to have and the above made no difference to me at all.
I currently have a model 7(7mm-08) and a Savage (270). I am considering buying something in the 30 cal range for elk. I want something I can use for both elk and mule deer. I origian;;y wanted a 338 but thought that might be a little too much recoil for what I need. I narrowed my choices down to 300winmag, 300wsm, and the 300RUM. From what I have been reading and hearing I am leaning towards the 300wsm. I am sure they will all work just fine. I like the weight and barrel length of the Tikka(T3) I think it would be a great choice for backpack hunting or long days of walking.
I have not shot a 300 so I don't know how bad the recoil is but I would for sure replace the recoill pad with a limbsaver or just one of the slip on ones from walmart. They are made by limbsaver but labeled winchester and cost half as much. Another thing I recommend with the Tikka is replacing the factory rings with something better like the gamereaper one piece for about 50 bucks. They are a lot more solid and seem to be the only complaint with the Tikka rifle.
I purchased a Tikka T3 in .300WSM before my first trip west for mule deer. Although I do not still own that rifle, it was a nice rifle and plenty accurate for any hunting situation. I found I was not a big fan of the synthetic parts though. If I was to buy that same rifle again, I'd opt for the .300 WM, as it is the same size action (as already mentioned) and the longer version has just a tad more juice with the heaviest (180 & 200gr) loads commonly found for a .300 mag and also may be a bit easier to find and less expensive in the ammo department as well.
Nothing wrong with a .300SM (I still own one in a Rem 673), but I believe you loose any possible advantage when it's housed in the same action length as a standard length magnum that's been around for as long as the .300WM has.
As the allure of hunting big whitetails becomes more and more a passion for many, we are finding that the recent (historically speaking) popularity of hunting deer from a tree stand is becoming the way to do it. I'll make no statement either for or against that technique here. This will be simply an essay on what I feel are some outstanding rifles for tree stand use.
Before we go even one more step, let's all remember that safety is first and foremost for anyone wanting to hunt...